This 5 year study will conduct a randomized clinical trial of a gender and culturally tailored theory-based behavioral risk reduction intervention for men and women who are receiving sexually transmitted infection (STI) diagnostic and treatment services from two different types of STI treatment providers in two provinces in South Africa. As many as one in five South Africans is HIV positive and there are an estimated 1,500 new HIV infections in South Africa each day. The experimental intervention in this study was developed by South African and US investigators and pilot tested in South Africa. The intervention is grounded in the experience of South African health service providers, Social Constructionist Theory of Gender, empirical research on AIDS-related stigmas, and elements of a social cognitive theory of health behavior change. The intervention consists of a single 60-minute risk reduction counseling session delivered within the context of STI services. The study will recruit 200 men and 200 women from four STI clinics (N = 1600), two dedicated STI clinics in urban centers and two primary care clinics in townships. Participants will be STI clinic patients over age 18 that have been treated for a previous STI. Participants will be baseline assessed and randomized to receive either (a) the 60 min theory-based and culturally tailored risk reduction intervention or (b) a time and contact matched standard of care HIV and health education session. Participants will be followed for 15 months post intervention. Assessments will be conducted using computer assisted interviews (ACASI). The randomized trial will determine the efficacy of the risk reduction intervention for South African men and women receiving STI clinic services. Outcome analyses will include differences between .conditions on new STI diagnoses over 15 months. We will also test the mediating effects of gender attitudes and beliefs, AIDS stigmas, information, motivation, and behavioral skills constructs on intervention outcomes. Results of this research will therefore test a clinic-based HIV prevention intervention model that is urgently needed in South Africa.